


Pros and Cons

by fuzipenguin



Series: Kinktober 2020 [18]
Category: Transformers Generation One
Genre: Established Relationship, M/M, Other, Referenced Experimentation, Sticky Sexual Interfacing (Transformers), Tentacle Dick, Tentacle Sex, Tentacles, Twincest
Language: English
Status: Completed
Published: 2021-03-18
Updated: 2021-03-18
Packaged: 2021-03-26 19:20:23
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,332
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/30110775
Author URL: https://archiveofourown.org/users/fuzipenguin/pseuds/fuzipenguin
Summary: Jury's still out, but Sideswipe is started to get an inkling of his decision at the end of it all.
Relationships: Sideswipe/Sunstreaker (Transformers)
Series: Kinktober 2020 [18]
Series URL: https://archiveofourown.org/series/2194158
Comments: 2
Kudos: 20





	Pros and Cons

**Author's Note:**

> 18\. Tentacles

Living your life as a spark split twin has its pros and cons.

Considered too much to handle by parents when only days old and abandoned at an orphanage? **Con.**

Never being alone, regardless of the distance separating you and your twin? **Pro**.

Called abominations, freaks of nature, and unstable? **Con.**

Knowing what love is from the instant you were unfurled? **Pro**.

Becoming a target for mad scientists’ weird and downright disturbing experiments? **Con.**

Learning that one of the experiments you had been submitted to while were in an induced coma was a modification to your interface array resulting in a spike with tentacles?

… well, that was still up in the air, actually.

“Is this ok?” Sideswipe gasped, bracing himself on his elbows and worriedly staring into his twin’s face.

“Yes. For the eighth time, _yes!_ ” Sunstreaker barked, wrapping a leg around Sideswipe’s waist and pulling him closer.

Sideswipe’s main spike core slid even deeper, and he groaned when he bottomed out, unable to go any farther. The eight new encircling segments of his spike which arose from the inner lining of his housing writhed across Sunstreaker’s frame, each supplying additional lines of sensory coding to his processor. One continually curled and uncurled around Sunstreaker’s anterior node, squeezing gently. Another two leisurely thrust in and out of Sunstreaker’s aft port in an arrhythmic pattern. Two more slid up and down Sunstreaker’s spike in a concentrated effort while another teased at the transfluid opening, tentatively slipping inside.

The final two had slithered their way beneath Sunstreaker’s hood at the very beginning, wrapping around Sunstreaker’s spark casing and nearly giving Sideswipe a panic attack. He finally had determined based on the way they felt warm and swollen and glutted with charge that they were absorbing the ambient energy his brother’s spark was giving off. Frightening at first thought, but ultimately harmless.

“Oh, slag,” Sunstreaker said faintly, raising his head up and staring down the length of his frame.

“What? What?!” Sideswipe asked, his entire body trembling with the influx of sensation. If he had enough practice, he thought he could eventually control all eight of the tentacles but as of yet, he could really only work one or two at a time. The others just seemed to do their own thing, potentially fueled by Sideswipe’s base interface coding. Or maybe there was still foreign coding that the medical team had missed.

He certainly hoped not. Everything felt really, _really_ good and it would suck if he ended up killing his twin while interfacing him with his brand-new tentacle-spike.

“It’s… you’re… don’t you feel that?” Sunstreaker asked. He raised his chin, gaze meeting Sideswipe’s. A blissful expression spread across his face and he relaxed back down into the covers, biting his lower lip.

“Feel what?” Sideswipe asked, but a second later, he understood what Sunstreaker meant. His spike was in the process of segmenting further, each portion pressing against Sunstreaker’s inner walls. The metal became as malleable as valve lips and molded against every bend and curve. The pieces… moved… and Sideswipe and Sunstreaker both cried out as the segments started writhing and maybe even… sucking?

“Oh, Primus…” Sunstreaker groaned, hanging on to Sideswipe’s shoulders for dear life. “It’s… there’s one…”

Sideswipe felt it distantly, the one remaining piece of his spike which seemed to be searching for something on the floor of Sunstreaker’s valve. It finally found what it wanted, and it shot forward, adhering to whatever it was with a strong suction. Through pleasure-slitted optics, Sideswipe watched his twin throw back his head and cry out in overload, a rush of blue sparks racing down his frame. As his valve started spasmodically clenching in an automatic attempt to draw in transfluid to his gestational tank, Sideswipe felt that single length force its way past what he now recognized as Sunstreaker’s tank opening.

Panicking a little, Sideswipe tried pulling back, but the tentacle tip spiraled open, latching on just behind the rim and pushing the opening wider until it felt large enough that his regularly sized spike could fit through it. He was scared that Sunstreaker would be in pain, but his brother just convulsed with another shouting overload.

Sideswipe didn’t know what to think at this point. Why was his spike doing this? It felt good as the Pit, but what was the purpose?

Then something deep in his lower belly throbbed and Sideswipe’s mouth dropped open at the sudden sharp sting of pleasure that accompanied it. “Sunny… Sunny, something’s…”

“It’s ok… it’s ok, I’m… I’m not hurt…” Sunstreaker gasped, sending reassuring pulses across their bond.

Sunstreaker had been intrigued by Sideswipe’s new spike from the get-go, whereas Sideswipe had viewed it in distrust. He hadn’t wanted to use it because what good could come of a Decepticon altering one’s interfacing anatomy? 

Apparently, a lot, judging by the rapid buildup of pleasure in Sideswipe’s groin. And now he was kind of glad that Sunstreaker had convinced him to try interfacing again.

“Frag… frag, I think… I think I’m gonna come…” Sideswipe whimpered, his pelvis instinctively hunching forward in tiny little jerks.

“Do it… Sides, do it,” Sunstreaker urged. “Let me feel it. I want to feel it…”

He sounded drunk, and Sideswipe wondered if his overloads had been _that_ good or if there was something else happening with this new process. Was Sideswipe secreting something, something which would make a partner more receptive?

The momentary worry quickly faded away when something deep inside him clenched down tight and then abruptly released. Sideswipe’s arms gave out and he collapsed down atop his twin moaning deliriously as what he assumed was transfluid spurted down the main tentacle directly into Sunstreaker’s tank.

The fluids kept coming, wave after wave, accompanied by a full body spasm of bliss which blanked out Sideswipe’s processor. His outer tentacles continued working Sunstreaker’s frame, thrashing with unnatural speed and ferocity and Sideswipe lost consciousness to the sound of his twin crying out repeatedly.

\--

His chronometer told him only fifteen minutes had passed between him passing out and opening his optics again. In that fifteen minutes, Sideswipe could have sworn an enemy combiner had come in and trampled him half to death.

He felt sore and weak, body barely able to respond to the signal to twitch his fingers, wriggle his pedes… anything.

“… Sides? You awake?”

Sunstreaker’s voice rumbled up through his cheek and Sideswipe rebooted his optics four times until his vision finally became clear. “… you ok?” he croaked, staring at Sunstreaker’s shoulder.

A warm hand slid down Sideswipe’s back and he closed his optics again, enjoying the soothing touch.

“I kept telling you… I’m fine,” Sunstreaker replied. “You on the other hand… you haven’t moved in a while and were barely venting. I’d have thought you were dead except I could still feel you in the bond.”

“I think I did die,” Sideswipe replied. With a determined intake of air, Sideswipe struggled to get his arms back under himself and he laboriously pushed himself upright. His twin appeared fine to Sideswipe’s optics. He felt more than fine along their link when Sideswipe probed it. Mellow and relaxed and utterly sated.

“Your… little friends… retracted right after your overload,” Sunstreaker said, bracing Sideswipe’s shoulders. “The main one too, I guess you could call it. After it was done completely emptying your tank into me, that is.”

Sideswipe slipped off his twin’s body and landed onto his hip, blinking hazily at Sunstreaker until his statement sunk in. Then he stared at the way Sunstreaker cupped his lower abdomen, the way the plating bowed outward a little.

“Damn,” he said faintly, reaching out and tracing the curve of it. “So that’s the goal of all… this?”

Sideswipe gestured down at his groin. Sunstreaker shrugged.

“Well, our species _does_ have a really low conception rate,” he pointed out.

Huh.

Experimented upon without consent. **Con.**

The intended purpose of the experiment and the actual result?

… Sideswipe had to go with ‘ **pro** ’ for this one.

~ End


End file.
